A conventional arrangement is described with reference to FIG. 15. FIG. 15 is a sectional view of a conventional loudspeaker. As shown in FIG. 15, magnet 101 is sandwiched between top plate 102 and yoke 103 to form inner magnet type magnetic circuit 104. To yoke 103 in this magnetic circuit 104, frame 106 is connected. To the periphery of this frame 106, first diaphragm 107 is attached. To this first diaphragm 107, voice coil 108 is connected. Voice coil 108 is fitted in magnetic gap 105 in magnetic circuit 104.
Further, panel 109 is connected to the periphery of frame 106. To this panel 109, substantially planar second diaphragm 110 is attached. Hermetic space 111 acoustically couples first diaphragm 107 and second diaphragm 110 to form loudspeaker 113.
Such a conventional art is disclosed in Japanese Patent Unexamined Publication No. 2003-179988, for example.